As far as denim goes, you can use sandpaper to accelerate wear along seams and around the various things in the pockets, but beyond that I don't know of any personal way to distress denim jackets other than wearing them.

That said, some jeans are hand-distressed, are they not? And if so, I guess that process could be replicated, but it's probably very labor-intensive. You might want to post this in Streetwear.

Does it really bother you all so much that a thread gets 5 posts on it before it gets moved to the more appropriate forum? The next person to say "Streetwear please," gets banned. The iron fist of death is upon you all. Just kidding of course.

I guess one could replicate the 'sitting lines' in denim by ironing some creases in and / or using some sandpaper to make them stand out. Some acid should work too if you have your kids chemistry set with acids in it...

Here's how to distress your jeans: Wash the jeans a few times to get them nice and soft. Use something abrasive on spots where you want the jeans to look worn - sandpaper, a pumice stone, or a cheese grater should all do the trick, depending on the degree of distress you're after. Try using some bleach to lighten your jeans in places where they would naturally fade. Look at old jeans to see where they naturally distress. You might want to experiment on some older jeans first.

We had some posts a while back on distressing jeans. I don't think you should wash them first thing. You should first wear them a bit so they get creases where they naturally appear. Then you can use sandpaper and/or dilute bleach to highlight the creases and other wear areas. Then wash them and see what you get. The other stuff with pumice, cheese grater, bench grinder, whatever is also an option.